Supplementary designations

The designation suffixes used to identify certain features of SKF double row cylindrical roller bearings are explained in the following.

B

Present standard design with brass cage of double pronged type

BK

B + K

CN

Normal radial internal clearance; normally only used together with an additional letter that identifies a reduced or displaced clearance range
H Reduced clearance range corresponding to the upper half of the actual clearance range
L Reduced clearance range corresponding to the lower half of the actual clearance range
M Reduced clearance range corresponding to the two middle quarters of the actual clearance range
P Reduced clearance range corresponding to the upper half of the actual clearance range plus the lower half of the next greater clearance range
The above letters are also used together with the clearance class suffixes C2, C3, C4 and C5

C1

Radial internal clearance smaller than C2

C2

Radial internal clearance less than Normal

C3

Radial internal clearance greater than Normal

C4

Radial internal clearance greater than C3

C5

Radial internal clearance greater than C4

F

Roller-centred machined steel cage of double pronged type

FA

Outer ring centred machined steel cage of double pronged type

FB

Inner ring centred machined steel cage of double pronged type

HA1

Case hardened inner and outer rings

HA2

Case hardened outer ring

HA4

Case hardened rollers, inner and outer rings

HB1

Bainite hardened inner and outer rings

HB2

Bainite hardened outer ring

HB3

Bainite hardened inner ring

K

Tapered bore, taper 1:12

KTN9

K + TN9

K30

Tapered bore, taper 1:30

M

Two-piece machined brass cage, roller centred

P4

Dimensional and running accuracy to ISO tolerance class 4

P5

Dimensional and running accuracy to ISO tolerance class 5

P6

Dimensional and running accuracy to ISO tolerance class 6

SP

Special precision class for machine tool bearings; dimensional accuracy approximately to P5, running accuracy approximately to P4